This invention relates to an electronic timepiece in which the reliability of the electrical connection of terminals made when a display unit is fitted diagonally into a housing is improved.
The construction of a related art electronic timepiece is shown in FIG. 5. The related art electronic timepiece generally has a structure in which a display unit 511 formed by holding in a housing 515 a liquid crystal panel 516, an electroluminescence panel (which will hereinafter be referred to as xe2x80x9cEL panelxe2x80x9d) 517, and a coiled spring 514 electrically connecting the EL panel 517 and a circuit board 512 together; and a driving circuit mounted with an integrated circuit and electric elements so as to supply an electric signal to the liquid crystal panel 516 and EL panel 517 are connected together by conductive rubber, a photoseal and a coiled spring.
In the electronic timepiece of such a construction, the display unit 511 is combined with the circuit board 512 as the display unit 511 is lowered vertically with respect the circuit board 512, so that a load is imparted to contact terminals, such as the conductive rubber 518 and coiled spring 514 vertically as well. Therefore, positions of the coiled spring and conductive rubber do not horizontally shift when these parts are bent.
In order to fit the display unit into a case in the related art electronic timepiece after the display unit is set diagonal with respect to the case so as to prevent the display unit from contacting other parts, such a display unit fitting operation is carried out as the display unit is inclined. Therefore, a load is imparted to the contact terminals diagonally, and the coiled spring and conductive rubber are locally deformed or caught on a free end of a terminal guide of the housing. When the display unit is further combined with the resultant product, a load is imparted vertically to a portion between the free end of the terminal guide of the housing and contact terminals. Consequently, a level of the frictional force of the driving circuit and electric terminals becomes higher than that of a force by which the electric terminals can move in a horizontal direction owing to the elastic deformation thereof, so that the display unit is fitted in the case with the electric terminals including coiled springs and conductive rubber slipped in the horizontal direction. This gives rise to problems of a slippage of the terminals from a predetermined pattern of the driving circuit, and a failure to electrically connect the driving circuit to the liquid crystal panel and EL panel.
The present invention has been made in view of these circumstances, and is to provide an electronic timepiece in which a horizontal slippage of contact terminals occurring when a contact terminal-mounted display unit is fitted diagonally in a case is suppressed and the electrical connection of the terminals is secured.
The invention provides an electronic timepiece comprising a liquid crystal panel, an electroluminescence panel provided on a rear surface of and adapted to illuminate the liquid crystal panel, electric terminals one end of each of which is electrically connected to a rear surface of the electroluminescence panel, and the other end of each of which is electrically connected to a circuit board, and a display unit housing holding the liquid crystal panel and electroluminescence panel therein, and having guide holes for inserting the electric terminals thereinto and retaining the same therein, the guide holes in the display unit housing having bores thereunder the diameter of each of which is larger than that of each of the guide holes so as to prevent a force exerted on the electric terminals when the electric terminals are inserted into the guide holes during an operation for diagonally fitting the display unit housing into a case with the liquid crystal panel, electroluminescence panel and electric terminals in a firmly combined state from causing the electric terminals in the mentioned state inserted into the display unit housing to slip in a horizontal direction.
By providing the bores, slippage of the electronic terminals in the horizontal direction when the display housing is fitted diagonally in the case is prevented.
The invention also provides an electronic timepiece, in which xcex2 is assumed to be an angle at which each of the electric terminals of a length L1 and an outer diameter D1 falls in the relative guide hole, which has a length L2 and a diameter D2, when the display unit housing is fitted in the case diagonally at an angle xcex1, a diameter D3 of the bore then having the following relation to the other sizes.
D3=D2+2xc3x97(L1xe2x88x92((L2)2+(D2xe2x88x92D1)2))xc3x97(sin xcex2+tan xcex1xc3x97cos xcex2) 
xcex2=TANxe2x88x921((D2xe2x88x92D1)/L2) 
Since the bores have the above-described relation to other parts, the bores have not to be enlarged to a level higher than a required level.
The invention further provides an electronic timepiece, in which the liquid crystal panel is a film liquid crystal panel, the film liquid crystal panel being connected to the circuit board by film-like materials, the film-like materials by which the film liquid crystal panel and circuit board are connected together having a plurality of different lengths.
The invention furthermore provides an electronic timepiece which is an electronic timepiece using a display unit housing which retains electric terminals of coiled springs which electrically connect an EL panel to a driving circuit, each of guide holes for the electric terminals being formed so that the guide hole has at a driving circuit-side portion thereof a tapering bore a diameter of which is set to a level determined on the basis of an angle at which the electric terminal of the coiled spring diagonally contacts the driving circuit when the display unit housing is diagonally fitted in a case.